I have a manager who has created a WhatsApp group for his team. I personally do not like to use my own phone for work related things. (I have Slack and Teams installed so you can reach me through any of these apps, I just do not want to give my phone number). How can I force my manager to use corporate approved communication tools instead of WhatsApp? It's worth mentioning that we all have NDAs signed and sharing images or work related information (I'm a developer who works closely with finance, sales and FP&A teams, so the information is very sensitive) on personal devices could be considered an NDA violation. I already spoke with him and sent him an email with this last concern in the hope he would change to any of the company-approved tools for communications with no success.
How can I convince my manager to use corporate approved communication tools instead of WhatsApp?